• Hercules Serial Port Monitor
• Hercules Serial Monitor
• Hercules Serial Monitor App
• Hercules Serial Monitor Camera

1.01 What is Hercules?

1.01 What is Hercules? Hercules is a software implementation of the System/370, ESA/390 and z/Architecture mainframe architectures. Hercules runs under Windows and Linux, as well as under various other Unix or Unix-like systems on Intel Pentium and other hardware platforms including Alpha, Sparc, and Mac. Hercules SETUP is useful utility including terminal for the Serial port (RS232 or RS485), UDP/IP and TCP/IP (Client or Server). Implemented Serial Terminal works with the Virtual Serial Ports,. Hercules SETUP is a lightweight tool developed to work as as a terminal which can handle serial ports, UDP/IP and TCT/IP protocols. It displays a user-friendly interface that has a tabbed. The Hercules / MDA plug is indeed the same physical as the RS-232 serial port (although 25 pin serial was also used) but the signals are very different. It's absurdly expensive to use this signal for anything these days as the only usage left is industrial but converters and even LCD monitors exist. DJControl Instinct P8 is compatible with:. Djuced 40. VirtualDJ Pro 8. PCDJ Dex 3. Future.dj pro. Traktor Pro 2.9 & higher (MIDI mapping on support.hercules.com). DJay Pr. The HW group product portfolio includes three major domains: Environmental, system and process monitoring devices; technology for IP based serial interface system control and data logging and Access Systems.

Hercules is a software implementation of the System/370, ESA/390 and z/Architecture mainframe architectures. Hercules runs under Windows and Linux, as well as under various other Unix or Unix-like systems on Intel Pentium and other hardware platforms including Alpha, Sparc, and Mac.

Hercules Hardware Complete line of hardware, fittings, chemicals, supplies and automotive products.

1.02 So what exactly does that mean?

It means that your PC can emulate an IBM mainframe processor. The mainframe can range from a System/360 to a z10 - running in 'S/370' mode, 'ESA/390' mode, or 'z/Architecture' mode.

Hercules executes S/370, ESA/390, and z/Architecture instructions and channel programs. It emulates mainframe I/O devices by using PC devices. For example, 3390 DASD devices are emulated by large files on your hard disk, and local 3270 screens are emulated by tn3270 sessions. (Note: Not all 370 and 390 features have been implemented in Hercules. See the list of particulars later in this document. Also, certain non-standard models, 360/20s, and the 360/67 virtual memory mode are not emulated.)

Hercules implements only the raw S/370, ESA/390, and z/Architecture instruction set; it does not provide any operating system facilities. This means that you need to provide an operating system or standalone program which Hercules can load from an emulated disk or tape device. You will have to write the operating system or standalone program yourself, unless you can manage to obtain a license from IBM to run one of their operating systems on your PC, or use IBM programs and operating systems which have been placed in the public domain.

1.03 Is it functional enough to run production work?

Hercules has never claimed to be a production-capable system. It was always meant to be a system programmer's toy. Having said that, it's now become good enough to run a wide range of software without problems, and there are reports that it has been used to run production work in some parts of the world.

1.04 What are the licensing restrictions for Hercules?

Hercules is a copyright work which has been made generally available, subject to the terms of theQ Public License. In essence this allows free use and distribution of the program for personal and commercial use. You may not distribute modified copies of the program, but you may distribute your own patches along with the program, provided that you also grant the maintainer permission to include those patches in future versions of the program. You may not copy any portion of the source code for use in any other program.

Hercules is not, repeat, not GPL software! The GNU General Public License is a Unix/Linux software licensing agreement, which we, the authors, will not participate in. We believe that the QPL, which has been certified as compliant with theOpen Source Definition, provides the benefits and protections of open source for both users and developers, without the political baggage that has come to be associated with the GPL.

2.01 Can it run z/OS, z/VM, z/VSE?

Yes. Hercules is a software implementation of z/Architecture, and so it is capable of running z/OS, z/VM, and z/VSE. Hercules also implements ESA/390 (including SIE) and so it can run OS/390, VM/ESA, and VSE/ESA, as well as older versions of these operating systems such as MVS/ESA, MVS/XA, VM/SP, VSE/SP, etc.

But (and this is a big but), these operating systems are all IBM Licensed Program Products, whose conditions of use generally restrict their usage to specific IBM machine serial numbers. So you cannot just copy these systems from work and run them on your PC.

2.02 What operating systems can I run legally?

Most 3rd party operating systems like Linux/390, z/Linux and TELPAR are covered under their own free license and can therefore run under Hercules without any legal problems.

OS/360 (PCP, MFT and MVT) is in the public domain, as far as we know. The status of OSes for which IBM did not charge a license fee is somewhat murky; these include MVS 3.8, VM/370 release 6, and DOS/VS release 34.

The legal status outside the USA, where something like public domain or software without copyright doesn't exist, is 'copyrighted software provided at no charge'. It is a known fact that vendors like Amdahl, Hitachi, Nixdorf and others modified those operating systems, and distributed them as their own OS for their own hardware, without asking IBM for permission. But law had been changed over that time, so its not clear if the same legal status applies in your country right now.

Rick Fochtman managed to obtain a letter from IBM that he is allowed to distribute OS/360. Try to ask your salesdroid for a similar letter for VM/370, MVS 3.8j or DOS/VS next time they want to sell you a major upgrade.

OS/390, z/OS, and other ESA or z/Architecture operating systems are definitely licensed to a particular machine. Therefore, in practice you cannot run any classic ESA or z/Architecture operating system on your PC unless you can obtain a license from IBM allowing you to do so. It is believed that there are, however, four ways you could run z/OS, z/VM, z/VSE, OS/390, VM/ESA, or VSE/ESA under Hercules using currently available licenses:

1. Running under Linux on the Pentium processor of a P/390 which is licensed to run the OS.
2. Running under Linux/390 on a mainframe which is licensed to run the OS.
3. Running under the terms of a disaster recovery provision of the OS license (but I really don't recommend depending on Hercules to be your disaster recovery solution!).
4. Using the IBM OS/390 or z/OS DemoPkg, which is available only to IBM employees and IBM Business Partners.

2.03 What other programs will run under Hercules?

Any program which uses the S/370, ESA/390, or z/Architecture instruction set, as implemented in Hercules. Some special utilities in the form of standalone programs are known to run well. I can particularly recommend Jan Jaeger's excellent standalone editor (ZZSA) which is included in the Hercules distribution, or it can be downloaded fromhttp://www.cbttape.org/~jjaeger; I use it regularly to look at DASD while debugging an OS installation, which is just what it's designed to do. Note: ZZSA runs in ESA/390 mode. See Jan Jaeger's website for more information and special logon procedures.

2.04 Where can I obtain OS/360 ?

1. Rick Fochtman's OS/360 archive CD is now obtainable by download from these locations:

• http://www.jaymoseley.com/hercules/install.htm

2. If you are interested in obtaining a copy of the CD itself, contact Rick Fochtman at rfochtman@ync.net.

3. Alternatively, you can download the OS/360 Y2K Starter package from http://open360.copyleft.de/OS360/Download.html which contains a full featured MVT system on a 3330 image, with some minimal documentation. The configuration is that of a 370/158 with 4 megabytes of main storage, running OS/MVT Release 21.0. The same site also offers a MVTDBL volume and a Builder package for those who like to participate in OS/360 nucleus hacking.

4. Jay Maynard's 'IBM Public Domain Software Collection' at http://www.ibiblio.org/jmaynard/ contains copies of the OS/360 Release 21.8 distribution tapes.

2.05 Where can I obtain MVS 3.8 ?

The Original MVS 3.8 distribution as it was first used came from

who advise using the mirrors at

Several people have generated a functional MVS system from this archive :

2.05 Where can I obtain VM/370 ?

The VM/370 page at cbttape.orgcontains download links for the Andy Norrie VM 4-pack system andthe Bob Abeles VM/370 R6 distribution.

2.07 Where can I obtain DOS/VS ?

I've put the DOS/VS r34 install tape on my site. It'll expand to a 21 MB AWSTAPE file, dosrel34.aws. You need the Coverletter to install it. Read the relevant postings of the Hercules mailing list first, as the install process is quite obscure.

You can grab those files at :

2.08 Where can I obtain Linux/390 ?

The best starting point for information about Linux for S/390 and Linux for zSeriesis http://www.linuxvm.org/

2.09 Where can I find documentation?

TheCreating Hercules DASD document describes various methods of creating and loading virtual DASD volumes.

I've produced a document describing how to build an OS/360 system on Hercules, called 'OS/360 on Hercules'. It can be found at

• http://www.conmicro.com/hercos360/hercos360/.

This will build an MVT system without TCAM/TSO, but with two 3270 consoles. You will need Malcolm Beattie's 'Guide to Using 3270 Consoles and Terminals for Hercules' with this MVT version.

The N.U.D.E guides can be found at :

• http://www.kiyoinc.com/hercdoc.html.

IBM provides only current documentation, ...
but many things haven't changed since 1964 :

3.01 What PC hardware do I need to run Hercules?

Classic IBM operating systems (OS/360, MVS 3.8, VM/370) are very light by today's standards and will run satisfactorily on a 300Mhz Pentium with as little as 32MB RAM.

Anything more up-to-date, such as Linux/390 or OS/390, requires much more processing power. Hercules is CPU intensive, so you will want to use the fastest processor you can get. A 2GHz Pentium, preferably with hyperthreading, will probably provide acceptable performance for a light workload. If you can afford a multiprocessor system, so much the better. Hercules makes extensive use of multi-threading to overlap I/O with CPU activity, and to dispatch multiple emulated CPU's in parallel.

For the latest 64-bit operating systems such as zLinux and z/OS, be aware that there is a performance penalty when Hercules emulates z/Architecture on a 32-bit processor such as the Pentium. If you are serious about running 64-bit then you will probably want to build Hercules for a 64-bit processor such as Alpha (DEC/Compaq/HP), or AMD64 (AMD Opteron, Athlon-64, Turion 64) together with a 64-bit version of Linux or PPC (Power Mac G5) with OS X.

Hercules does not depend on the Pentium architecture. I've built and run it successfully on a 500 MHz Alpha 21164, and others have run it on SPARC and S/390 (!) Linux systems. One guy has even run OS/360 under Hercules under Linux/390 under Hercules under Linux/390 under VM/ESA! The prize for the world's smallest mainframe probably goes to Ivan Warren, who claims to have run VM/370 under Hercules on an iPAQ 5450 handheld PDA.

You should provide enough RAM to accommodate your S/390 real storage (main storage plus expanded storage) in addition to the normal requirements of your PC's operating system. For maximum throughput, you should set your main and expanded storage sizes high enough to eliminate S/390 paging. S/390 storage is allocated out of your PC's virtual storage.

You also need enough hard disk space to accommodate the emulated DASD. A virtual '3330 model 1' disk drive will need about 100 megabytes of space for emulation (a 3330-11 will need about 200 megabytes). A 3380 'single density' model will need about 650MB, a 3390 model 2 needs about 2GB, and a 3390 model 3 needs about 3GB. If you use thecompressed CKD DASD feature, these sizes will shrink dramatically, usually to about 20 to 30 percent of the original size.

3.02 What sort of MIPS rate can I expect?

Thanks to the cumulative work of many individuals, including Valery Pogonchenko, Juergen Dobrinski, Albert Louw, Gabor Hoffer, Jan Jaeger, Paul Leisy, Clem Clarke, and Greg Smith, the performance of Hercules today is vastly better than it was 5 years ago.

Even on a Celeron 300 you should see an execution speed of 1 to 2 MIPS, which is enough to run OS/360 (MFT or MVT) or MVS 3.8 with a response time better than that of a 3033 from the 1970's. It's also fast enough to run VSE/ESA with an acceptable response time. On a more recent system with a 2GHz Pentium processor, you may see the system peak at around 30 MIPS which is enough to run Linux/390 or z/OS with a light workload.

Performance on server class machines is now fairly respectable. For example, on a dual-core Intel Xeon with hyperthreading (4 CPUs) running at 3.46GHz, you might expect to see a sustained MIPS rate of 40 to 60 MIPS. A dual-processor quad-core Mac Pro (8 cores, 3 GHz) will sustain over 150 MIPS. For anyone who is prepared to spend a considerable amount of money on their Hercules system, there are reports that a sustained 300+ MIPS has been achieved on an Intel Core i7 processor running at 3.75GHz using all four cores plus hyperthreading (8 CPUs).

Typical I/O rates of around 50 EXCP/second are reported on average hardware, with rates over 500/second achievable with hardware RAID.

3.03 What PC software do I need to run Hercules?

The following software platforms are supported:

NOTE: Since neither Windows XP x64 nor Windows Server 2003 are supported any longer by Microsoft either (extended support for both ended on April 2014 and July 2015 respectively), Hyperion support for them will be dropped in the very near future as well. All Hercules users running either of these operating systems are strongly encouraged to upgrade as soon as possible to Windows Vista or Windows 7 Professional SP1 x64 or greater.

You will also need tn3270 client software for the virtual 3270 console. The tn3270 client can run on the same machine as Hercules, or on any Unix or Windows box with a TCP/IP connection to the Hercules machine.

The supported and recommended tn3270 clients for Hercules are:

x3270 for Unix

x3270 is included with most Linux distributions, or you can download it fromhttp://x3270.bgp.nu/

Vista tn3270 for Windows

Vista tn3270 can be obtained fromwww.tombrennansoftware.com. The very modest license fee charged for this excellent 3270 emulator helps to support an independent software developer.

Brown University tn3270 for Macintosh

Brown University tn3270 is freely available. You can download it from http://www.brown.edu/Facilities/CIS/tn3270/. There is one setting that must be changed to use this program with some operating systems, especially MVS 3.8: Open a connection to Hercules, but before IPLing the system, go to the Session->Features menu and set 'Change embedded nulls to blanks' to 'No'. Click on 'OK'. Now, click on File->Save default settings... to make the setting permanent.

Other tn3270 clients, such as QWS3270, IBM Personal Communications, Attachmate Extra, or Dynacomm Elite should also work in most cases, but be aware that some tn3270 clients have bugs which make them unusable as OS/360 or MVS consoles.

3.04 What software do I need to build Hercules on Linux and Unix?

To build Hercules for Linux and other Unix-like environments (including Cygwin under Windows), you need to use the gcc compiler, version 3.x or above. You will also need a full set of GNU development tools, including recent versions of autoconf, automake, flex, gawk, gcc, grep, m4, make, perl, and sed. Refer to the util/bldlvlck file in the Hercules distribution for details.

3.05 What software do I need to build Hercules on Windows?

To build Hercules for the Windows native environment (without Cygwin), you need to use the Microsoft C/C++ compiler (MSVC) version 14.x or later. The 32-bit compiler and SDK are packaged as Microsoft Visual C++ 2008 Express (Version 15.x) available for download from Microsoft. Although no longer available for download, Microsoft Visual C++ 2005 Express (Version 14.x) may also be used. For further information, see Fish's MSVC Hercules Build page at http://www.softdevlabs.com/hercules-msvc-build.html Alternatively, the Microsoft Visual Studio 8.0 or 9.0 products may be used. To build Hercules for 64-bit Windows platforms you will need Microsoft Visual Studio 9.0 Professional.

3.06 Can Hercules be ported to run on other platforms?

With the introduction of autotools, we do make efforts to ensure Hercules builds and run on several different operating system platforms (mostly Linux, Windows, MAC, Solaris, and FreeBSD right now), but we of course simply cannot guarantee that it will run on every operating system platform out there.

If you want to make Hercules run on AS/400, OS/2, or whatever, then by all means go ahead. I welcome reports of any bugs or problems you find, but I probably won't fix problems if it means introducing platform-specific code, and I will not be able to test new releases against other platforms. Folks who have gotten it compiled on the BSDs report that the hardest part is removing the Linux-specific tape support.

The Hercules code is not intended to be specific to Intel hardware, so if you find any issues or faults related to running on other hardware (SPARC, Alpha, PPC, ...) under Linux, then I'm likely to be receptive to fixing that sort of problem. Issues related to Unix variants are less likely to be fixed however.

4.01 How can I create a virtual DASD volume?

The Creating Hercules DASD document describes various methods of creating and loading virtual DASD volumes.

4.02 Can I read a tape which was created on a mainframe?

Yes, indirectly. The mainframe tape must be converted to AWSTAPE format and then downloaded to your PC. Thetapeconv.jcl file in the Hercules directory contains a sample program which you can run under OS/390 on your mainframe system. It reads a file from tape and converts it to AWSTAPE format. Download the AWSTAPE file to your PC (making sure to choosebinary format for the download), and then add the downloaded filename to the Hercules configuration file as a virtual tape device. You will then be able to read the tape file from the virtual tape drive located on your PC.

Note: the 'tapeconv' program will not correctly process input tapes whose block size exceeds 32760! One symptom of this may be the message 'ADRY011E I/O ERROR - DEVICE NOT ATTACHED.0000,NA,00...00,0000' when attempting to restore from tape originally created using the default DF/DSS block size. The solution is to recreate the dump tape with DCB=BLKSIZE=32760.

4.03 Can I attach a PC tape drive to Hercules?

Yes. Hercules can read and write tapes on SCSI drives. I have tested this with 4mm DAT, QIC-1000, and 9-track drives.

4.04 Can I process mainframe tapes with Hercules?

Yes. It is possible to obtain 9-track open reel drives and 3480-type cartridge drives which attach to the SCSI bus. Hercules makes these appear to the operating system as channel-attached 3420 or 3480 devices, making it possible to read and write real mainframe tapes.

4.05 Can I create Assembler programs without a mainframe?

Yes. If you want to write Assembler (BAL) programs to run on Hercules, but you don't have access to a mainframe, then there are two interesting products which you can run on your PC to assemble programs:

The 'Tachyon 390 Cross Assembler' (http://www.tachyonsoft.com/tachyon )

With this assembler you can produce S/390-compatible object decks using your Linux or Windows PC. A high degree of HLASM compatibility, coupled with the ability to perform complex assemblies at lightning speed, make this a product which is well worth looking at. I have tried this assembler and it is truly amazing.

The 'Dignus Systems/C Compiler' (http://www.dignus.com )

This is a C compiler which runs under Windows or Linux and generates mainframe assembler code which you can then assemble using the Tachyon assembler.

Sam Golob wrote a fascinating review of these two products in the September 1999 issue of NaSPA Technical Support magazine.

5.01 What architectural features are implemented?

The following standard features of ESA/390 have been implemented:

• Address-Limit Checking
• Commercial Instruction Set
• Decimal Instructions
• Hexadecimal Floating-Point Instructions
• 24-bit and 31-bit addressing
• Key-Controlled Protection
• Page Protection
• Low-Address Protection
• Dynamic Address Translation
• 370-XA Channel Subsystem
• Channel Indirect Data Addressing
• Program Controlled Interruption (PCI)
• Channel Program Suspend/Resume
• Dual Address Space
• Access Register Mode
• Home Space Mode
• Branch and Save
• Conditional Swapping
• TOD Clock, Clock Comparator, and CPU Timer
• MVCS/MVCP/MVCK/MVCSK/MVCDK instructions
• TB/TPROT instructions
• LURA/STURA instructions
• BAKR/PC/PR/PT instructions
• Linkage Stack
• Compare and Form Codeword and Update Tree instructions

The following optional features of ESA/390 have been implemented:

• Access-List-Controlled Protection
• Binary Floating-Point instructions
• Branch and Set Authority
• Broadcasted Purging
• Checksum instruction
• Compare and Move Extended instructions
• Dynamic Reconfiguration
• Expanded Storage
• Fast Synchronous Data Mover Facility
• Floating-Point-Support Extensions
• Halfword-Immediate instructions
• Branch-Relative instructions
• Incorrect-Length-Indication Suppression
• Interpretive Execution (SIE)
• Move Inverse
• Move Page (Facility 2)
• MVS assists
• Operational Extensions: Console Integration
• Private Space
• Set Address Space Control Fast
• Service-call-logical-processor (SCLP) facility
• Square Root
• Storage-Protection Override
• Storage Key assist
• String instructions
• Subspace Group
• Compare Until Substring Equal
• Concurrent Sense
• Suppression on Protection with Virtual-Address enhancement
• Extended TOD clock
• Compression
• Perform Locked Operation
• Vector Facility
• Multiple Controlled Data Space (VM dataspaces)
• Extended Translation
• Extended Translation Facility 2
• Store System Information
• Cancel I/O Facility
• Program Event Recording
• Guest PER enhancement

The following optional features of z/Architecture have been implemented:

• HFP Multiply-and-Add/Subtract Facility
• Message Security Assist
• Long-Displacement Facility
• DAT-Enhancement Facility
• Extended-Translation Facility 3
• ASN-and-LX-Reuse Facility
• List-Directed Initial Program Load
• Modified CCW Indirect Data Addressing (MIDAW) Facility
• Extended-Immediate Facility
• Message-Security-Assist Extension 1
• Message-Security-Assist Extension 2
• DAT-Enhancement Facility 2
• Store-Clock-Fast Facility
• Store-Facility-List-Extended Facility
• ETF2-Enhancement Facility
• ETF3-Enhancement Facility
• PER-3 Facility
• TOD-Clock-Steering Facility
• Conditional-Emergency-Signal and Sense-Running-Status Facility
• Multiple Logical Channel Subsystems Facility
• Floating-Point-Support Enhancement Facilities(FPR-GR-Loading, FPS-Sign-Handling, and DFP-Rounding)
• Decimal Floating Point Facility
• IEEE-Exception-Simulation Facility
• Extract-CPU-Time Facility
• Conditional-SSKE Facility
• Compare-and-Swap-and-Store Facility
• Execute-Extensions Facility
• General-Instructions-Extension Facility
• Move-with-Optional-Specifications Facility
• Parsing-Enhancement Facility
• Compare-and-Swap-and-Store Facility 2
• Integrated 3270 (SYSG) Console
• Configuration-Topology Facility
• HFP-Unnormalized-Extensions Facility
• CMPSC-Enhancement Facility
• High-Word Facility
• Interlocked-Access Facility
• Load/Store-on-Condition Facility
• Distinct-Operands Facility
• Population-Count Facility
• Message-Security-Assist Extension 3
• Message-Security-Assist Extension 4
• Fast-BCR-Serialization Facility
• Enhanced-Monitor Facility
• Reset-Reference-Bits-Multiple Facility
• Access-Exception-Fetch/Store-Indication Facility
• Load-Program-Parameter Facility
• IPTE-Range Facility
• Enhanced-DAT Facility
• Queued Direct I/O (QDIO)
• Interlocked-Access Facility 2

The following optional features of z/Architecture have not yet been implemented:

• PFPO Facility
• Restore-Subchannel Facility
• Integrated ASCII (SYSA) Console
• CPU-Measurement Counter Facility
• CPU-Measurement Sampling Facility
• Floating-Point-Extension Facility
• Nonquiescing Key-Setting Facility
• Enhanced-DAT Facility 2
• Local-TLB-Clearing Facility
• PER Zero-Address-Detection Facility
• Processor-Assist Facility
• Transactional-Execution Facility
• Warning-Track-Interruption Facility

The following standard feature has not yet been implemented:

• Clear I/O (full functionality for S/370)

The following optional features have been partially implemented:

• Channel-Subsystem Call
• VM/370 assists

The following features are not yet implemented, either due to lackof documentation, limited host system capability, or lack ofsupporting hardware:

• Asynchronous Data Mover Facility
• Asynchronous Pageout Facility
• Coupling Links
• ESCON
• FICON
• MIF (Multiple Image Facility)
• Extended Sorting
• External Time Reference (Sysplex Timer)
• ICRF (Cryptography)
• Operational Extensions: Automatic Reconfiguration, StorageReconfiguration, SCP-initiated Reset, Processor Availability
• PR/SM
• Program-Controlled re-IPL

Hercules is compliant with IBM's ALS-1, ALS-2 and ALS-3architectural level sets to the degree necessary to run all OS/390versions through 2.10 and known versions of z/OS in both ARCHLVL 1and ARCHLVL 2 mode, and Linux and z/VM in both ESA/390 andz/Architecture mode.

6.01 Who are the Herculeans?

The following people are among those who have contributed to thisproject, either as coders or as testers or both:

And thanks for support and encouragement from:

If anyone feels they have been unfairly omitted from either of theselists, please let us know.

7.01 Where can I obtain technical support?

Please see our Technical Support web page.

Last updated $Date$ $Revision$

The Hercules Graphics Card (HGC) is a computer graphics controller made by Hercules Computer Technology, Inc. that combines IBM's text-only MDA display standard with a bitmapped graphics mode. This allows the HGC to offer both high-quality text and graphics from a single card.

The HGC was very popular, and became a widely supported de factodisplay standard on IBM PC compatibles. The HGC standard was used long after more technically capable systems had entered the market, especially on dual-monitor setups.

History[edit]

The Hercules Graphics Card was released to fill a gap in the IBM video product lineup. When the IBM Personal Computer was launched in 1981, it had two graphics cards available, the Color Graphics Adapter (CGA) and the Monochrome Display And Printer Adapter (MDA). CGA offered low-resolution (320x200) color graphics and medium-resolution (640x200) monochrome graphics, while MDA offered a sharper text mode (equivalent of 720×350) but had no per-pixel addressing modes and had a fixed character set.

These adapters were quickly found to be inadequate by the market, creating a demand for a card that offered high resolution graphics without compromising on text quality.^[1] The founder of Hercules Computer Technology, Van Suwannukul, created the Hercules Graphics Card so that he could work on his doctoral thesis on an IBM PC using the Thai alphabet, which was impossible at the low resolution of CGA or the fixed character set of MDA.^[2] It initially retailed in 1982 for $499.^[3]

Hardware Design[edit]

The original HGC was an 8-bit ISA card with 64KB of RAM^{[citation needed]} and a DE-9 output compatible with the IBM monochrome monitor used with the MDA. Like the MDA, it included a parallel interface for attaching a printer.^[4]

The video output is 5V TTL, as with the MDA card.^[5][6] Nominally, the Hercules card provides a horizontal scanning frequency of 18.425 ±0.500 kHz, and 50 Hz vertical.^[7]

The Hercules actually ran at two slightly different frequencies depending on whether it was running in text or graphics mode, due to the slight difference in horizontal resolution.^{[citation needed]}

Capabilities[edit]

The Hercules card provided two modes: an MDA-compatible monochrome text mode, and a pixel-addressable graphics mode at 720x348.^[8] This mode of the Hercules card used the same signal timing as the MDA text mode.

The Hercules graphics mode had a lot in common with the CGA high-resolution (640×200) two-color mode: the video buffer contained a packed-pixel bitmap (eight pixels per byte, one bit per pixel) with the same byte format, including the pixel-to-bit mapping and byte order, as the CGA two-color graphics mode, and the video buffer was split into interleaved banks, each 8 KB in size, as in the CGA graphics modes.

However, because in the Hercules graphics mode there were more than 256 scanlines and the display buffer size was nearly 32 KB (instead of 16KB as in all CGA graphics modes), four interleaved banks were used in the Hercules mode instead of two as in the CGA modes. Also, to represent 720 pixels per line instead of 640 as on the CGA, each scanline had 90 bytes of pixel data instead of 80.^{[citation needed]}

The 64 KB RAM of the HGC could hold two graphics display pages. Either page could be selected for display by setting or resetting a single bit in the Mode Control Register. Another bit, in a configuration register exclusive to the HGC, determined whether the second 32 KB of RAM on the HGC was accessible to the CPU at the base address B8000h. This bit was reset at system reset (e.g. power-on) so that the card would not conflict with a CGA or other color card at address B8000h.^{[citation needed]}

Use[edit]

In textmode, the HGC appears exactly like an MDA card.^[9]

Graphics mode required new techniques to use. Unlike the MDA and CGA, the PC BIOS provided no intrinsic support for the HGC. Hercules included extensions to IBM BASICA to add HGC support, called HBASIC,^[10] and Hercules cards came with a 'GRAPH X' application which enhanced the BIOS by adding Hercules graphics-mode support and even geometric drawing primitives.^[11]

Popular IBM PC programs at the time (such as Lotus 1-2-3 spreadsheet, AutoCAD computer-aided drafting, Pagemaker and Xerox Ventura desktop publishing, and Microsoft Flight Simulator) came with their own drivers to use the Hercules graphics mode.^{[citation needed]}

Though the graphics mode of the Hercules card was not CGA-compatible, it was technically similar enough to the two CGA graphics modes that eventually through the use of third-party drivers (TSRs) it could also work with programs written for the CGA card's standard graphics modes. As the Hercules card did not actually have color-generating circuitry, nor could it connect to a color monitor, color appeared as simulated greyscale in varying patterns.^{[citation needed]}

Clones of the Hercules appeared, including generic models at very low prices, usually without the printer port. Hercules briefly ran ads implying that use of generic clones of the Hercules card could damage the monitor.^[12]

Reception[edit]

The Hercules Graphics Card rapidly gained popularity, selling a half a million units by 1985,^[13] and even began shipping as standard hardware with some PC clones.^[8] Support in software was widespread.

Hercules Serial Port Monitor

Later cards[edit]

The Hercules Graphics Card was followed by several other Hercules cards.

Hercules Graphics Card Plus (HGC+)[edit]

The Hercules Graphics Card Plus (HGC+) was released in June 1986 by Hercules Computer Technology, Inc. at an original retail price of $299.^[14] It was an enhancement of the HGC, adding support for redefinable fonts called RAMFONT in MDA compatible text mode.^[15][16]

Hercules Serial Monitor

It was based around a specialty chip designed by Hercules Computer Technology, unlike the original Hercules Graphics Card which used standard components.^[17]

Software support included Lotus 1-2-3 v2, Symphony 1.1, Framework II and Microsoft Word 3.^[14]

Hercules Network Card Plus[edit]

In 1988 Hercules released the Network Card Plus, a variant of the Graphics Card Plus with an integrated TOPS/FlashTalk-compatible network adapter.^[18] Like the HGC+ it supported RAMFONT, but lacked a printer port.^[19][20][21]

Others[edit]

The unrelated Hercules InColor Card (April 1987) included color capabilities similar to the EGA, with 16 colors from a palette of 64. It retained the same two modes - 80×25 text with redefinable fonts and 720×348 graphics.

Hercules also sold the Hercules Color Card (not to be confused with the InColor Card), a CGA-compatible video board.This board could coexist with the HGC and still allow both graphics pages to be used. It would detect when the second graphics page was selected and disable access to its own memory, which would otherwise have been at the same addresses.

Clone boards[edit]

• Tseng ET-1000 board

• ATI Hercules-compatible card from 1986

• A Tamarack Microelectronics HGC-compatible card

Other boards offered Hercules compatibility.^[22]

Hercules Serial Monitor App

• SiS 86C12, 86C22
• ATI Small Wonder Graphics Solution, 18700, Graphics Solution Plus
• Tamarack Microelectronics TD3088A, TD3088A2, TD3088A3, TD3010, RY-3301, TD3010
• Yamaha V6366C-F, V6363-F, V6363
• Winbond W86855AF, W86855AF
• NEC μPD65042GD
• Tseng Labs ET1000-A
• DFI MG-150
• Hitachi HD6445P4, HD6845SP
• RAM MCG2502, MCG2502
• Proton PT6121T
• Acer M3127
• Sigma Designs 53C101+53C280A
• CM607P

Certain later models of the Tandy 1000 (such as the 1000 TL and SL) and the Epson Equity contained circuitry built into their CPU boards that supported Hercules display modes in addition to their standard CGA modes.

See also[edit]

References[edit]

1. ^Inc, InfoWorld Media Group (1988-09-19). InfoWorld. InfoWorld Media Group, Inc.
2. ^Inc, Ziff Davis (1989-05-16). PC Mag. Ziff Davis, Inc.
3. ^Inc, InfoWorld Media Group (1986-09-01). InfoWorld. InfoWorld Media Group, Inc.
4. ^Inc, InfoWorld Media Group (1982-09-27). InfoWorld. InfoWorld Media Group, Inc.
5. ^'IBM PC-Compatible EGA Video Reference'. Archived from the original on 2013-06-27. Retrieved 2007-08-22. 070822 nemesis.lonestar.org
6. ^'Monitor Ports'. 071105 whitefiles.org
7. ^'Industrial monochrome monitors 7' - 14''(PDF). Archived from the original(PDF) on 2007-02-02. 070822 adm-electronic.de
8. ^ ^abInc, InfoWorld Media Group (1989-06-26). InfoWorld. InfoWorld Media Group, Inc.
9. ^Wadlow, Tom (December 1983). 'The Hercules Graphics Card'. BYTE. p. 343. Retrieved 2013-10-20.
10. ^The Hercules Graphics Card, December 1983, BYTE Magazine(PDF). 1983.
11. ^Wadlow, Tom 'The Hercules Graphics Card', BYTE, Volume 8, Number 12, December 1983. Retrieved on 14 July 2017.
12. ^'Hercules ad from Byte Magazine April 1985'. Byte Magazine. April 1985.
13. ^Enterprise, I. D. G. (1986-06-23). Computerworld. IDG Enterprise.
14. ^ ^abInfoWorld 1 Sep 1986, p. 41, at Google Books
15. ^Elliott, John C. (2012-08-09). 'Hercules Graphics Card Plus: Notes'. Archived from the original on 2016-11-23. Retrieved 2016-11-23.
16. ^Inc, InfoWorld Media Group (1986-09-01). InfoWorld. InfoWorld Media Group, Inc.
17. ^'Inside the IBM PC: Before you consider the Hercules Graphics Card Plus consider the technology behind it'. Byte Magazine (Advertisement). 11. October 1986. Retrieved 2016-11-24.
18. ^Inc, InfoWorld Media Group (1988-03-21). InfoWorld. InfoWorld Media Group, Inc.
19. ^CW (1988-04-22). 'Hercules bringt neues PC-Board mit Ramfont: Grafik und Netzwerk auf einer Karte'. Computerwoche (in German). Retrieved 2016-11-24.
20. ^'Hercules Network Card Plus'. PC Magazine. 1988-05-31. Retrieved 2016-11-24.
21. ^Inc, InfoWorld Media Group (1987-10-26). InfoWorld. InfoWorld Media Group, Inc.
22. ^'VGA Legacy'. Archived from the original on 2014-06-29. Retrieved 2014-06-28.

Further reading[edit]

• Wilton, Richard (1987) Programmer's Guide To PC and PS/2 Video Systems, Microsoft Press, ISBN1-55615-103-9
• Hercules Computer Technology (1987) Hercules Compatibility Guide (a leaflet)
• 'Hercules graphics' definition, Wi-FiPlanet.com
• How to Print Hercules Graphics SCREEN 3 to an Epson Printer, Microsoft.com
• Hercules Monochrome Graphics Adapter, Everything2.com

Hercules Serial Monitor Camera