Gepard – Part Five c): The Hardware, Phase 3

After the Gepard company went bust, one of the founders, Hermann Spille, founded HS Computer and continued providing Gepard hard- and software and even developing further cards. In this last phase, the 68020 cards were finished and put on the market. In this phase, most of the cards from the 2nd phase were still available. HS Computer was liquidated in 2009. Afterwards, no new Gepard component development or distribution seems to have taken place.

Third Phase: 1987: the 32-bit era

68020

68020 cards

There were two variants of this card. In April 1987 the first version appears. It sports a Motorola 68020 with 12.5 MHz, offers a socket for a 68881 FPU, and 128 kB SRAM. The problem with the Gepard architecture and 32 bit CPUs is that the used proprietary bus is a 16 bit bus providing mainly the signals of the 16 bit 68000 CPU. A 32 bit CPU needs a 32 bit bus if you want to connect CPU and RAM at full speed. In a backplane-based system like the Gepard CPU and RAM reside on different cards. Now, unfortunately, you cannot change the bus in a backplane-based system because you would have to change a lot of hardware and still have the problem of backwards compatibility with the old 16 bit cards. So, the typical solution, also used here, is to put (some) RAM on the CPU card (where you can have 32 bit connections), and use the system bus for the rest of the system. The first version provides only a small amount of on-CPU-card RAM (128 kB) and tries to mitigate this small amount by using a faster RAM variant, namely SRAM. The bulk of the RAM is still residing in the separate RAM cards, connected by only 16 bits, but by caching memory in the SRAM now not every RAM access needs to pass the 16 bit bottleneck. Although not backplane-based system, the same problem and solution occurred also for the Amiga 3000 and Atari TT. They both sport the legacy 16 bit architecture of the Amiga and Atari ST, respectively. This means that both new systems basically contain an old system, but now have a 32 bit CPU. That’s why in both systems you have now two different types of RAM: old, 16 bit-connected RAM, and new 32 bit “Fast” RAM connected directly to the CPU.

The second version (in DEcember of 1987) of this card uses 16.5 MHz, has also a 68881 socket, and sports now an own 32 bit socket for a daughter memory card. At the same time, a 4 MB (D)RAM card is offered for this socket. This allows now to access all memory with 32 bit.

In the research of the Gepard history it occurred to me that probably from 1987 the 68020 Gepards were the cheapest 32 bit systems in Germany until the appearance of the Amiga 3000 and the Atari TT in 1990.

z80

Z80 card (“HD 64180 – Karte”)

This card contains a Z80-compatible HD 64180 processor that runs at 8 MHz. It provides also 256 kB of RAM. Additionally, it features a Centronics printer port and two serial ports. It is delivered with an LDOS called operating system that is compatible with CPM 80 V3.0.

burner

EPROM Burner

This card allows to program two EPROMs at the same time. This card has a cable that connects to a small external box with two EPROM sockets. The needed software is delivered with the card.

atari

“Atari” Graphics card
This graphics card was developed by a company that two of the other founders of Gepard founded. It offeres basically the monochrome graphics capabilities of the Atari ST having a resolution of 640*400 pixels black and white and have an interface where the 70 Hz Atari monitor (e.g. the SM 124) can be connected to. This card can also be used for generating text output instead of the 80-characters card.

Tags:

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s


%d bloggers like this: