Love on the buses: The S-100 and me
An illustrated affair
This Old Box Although the IBM PC had been released in August of 1981, the system of choice for true geeks in those days was a home-brewed computer based on the S-100 bus architecture.
I may have not been a bull geek in those days, but I was working on it - so I built one in 1982. It served as our family's computing workhorse for a few years, even after it was joined in our home office by an Apple Mac in 1984.
The S-100 bus was an outgrowth of the Altair 8800 of the mid-1970s - and, no, I'm not going to call the Altair 8800 the "first personal computer". There are so many competitors and such a vague history surrounding that claim that I'll let you folks dig into that contentious subject on your own.
First or not, the Altair 8800 did give rise to a bus technology that was eventually standardized - as much as anything was standardized in those early days - into the S-100 bus. Much of the popularity of the S-100 bus can be credited to the efforts of George Morrow - one of the true greats of the early days of personal computing - and his S-100 Bus Standards Committee.
It may not have been pretty, but it was a business powerhouse
Supported by broad range of systems, the S-100 bus made assembling your own system a relatively easy chore. First you opened up the back pages of Byte magazine, found an enclosure with enough slots, bays, and power that you might need, and wrote a check. Then you shopped for cards, drives, and cables.
Here in the San Francisco Bay Area, that latter chore was decidedly more enjoyable, as the quest led me to the San Jose Swap Meet, where companies and individuals put up makeshift tents or backed-up their pickup trucks, and sold everything from chips to cards to cables.
Inside there's plenty of room for cards, drives, and power supply
I recall that when I asked the guy from whom I bought a bargain $300 64KB RAM card - out of the back of his truck, by the way - about his warranty policy, he simply laughed. The suits hadn't yet tamed Silicon Valley.
So here's the system that I assembled, and which has been languishing in my basement since the early 1980s. Some basic specs:
- Size: 22 by 20.75 by 10.75 in. (55.9 by 52.7 by 27.3 cm)
- Weight: 77 lbs. (35.4 kg)
- 8-bit processor: 6MHz Intel 8085
- 16-bit processor: 8MHz AMD 8088
- Memory: 64KB SRAM
- Storage: Two 1024KB 8-inch floppy drives
- Ports: Three RS-232 serial, one Centronics parallel
- Operating system: CP/M 2.2
- Spreadsheet: SuperCalc
- Word processor: WordStar
- Database software: dBASE II
- Management utility: CP/M Power
- Price: $2,100 (£1,420) in 1982 dollars, or $4,630 (£3,130) in 2009 dollars
Next page: Let's put this puppy together
Everything old is new again...
So basically the floppy-emulator RAM card was my generation's version of the SSD. Except without that persistence without power thing...
This article made me nostalgic for Motorola's 6502 and then 680x0 family -- as a teenager earning spending money writing small business software on 6502 systems, interning writing assembler on 8086 embedded systems, and discovering the revolutionary 680x0 family at college, I was absolutely convinced that the elegant, orthogonal Motorola architecture would win out over the baroque Intel instruction set, or even its Zilog Z80 cousin... ah, the joys of youth...
As for the "what's the point?" whiners above... what exactly is your problem? Is there a shortage of space for articles? Was some other more interesting article pushed aside for this? Did you pay too much for an article you don't care about? Oh wait... this is free and online! So you're just making a fool of yourself complaining about it!
"wumpus , could not remember that name"
If you're running a Linux or BSD variant, try typing "wump" at a command prompt :-)
that's the name
wumpus , could not remember that name
But I do remember trying to decide on the s100 or a heath kit .
And the winner from Japan , boot leg Apple 2 mother BD...
thanks for memory lane down the Byte way
Windows 7 capable?
If Microsoft can trim down Windows 7 to run on this little beast, I'll buy that for a dollar.
Not really 16 bit8088 8086
Most S100 used 8080 originally and then later Z80 or 8085. Few used 8088/8086 as it wasn't really 16bit. 68000 was really the first S100 16Bit. I remember Cromemco UNIX like Cromix 5 years later on dual Z80/68000 "minicomputer".
the 8088 uses an 8085 8 bit data / 16 bit address multiplexed and 4 extra address bits on the 8088 for 1024K MAXIMUM. But the various peripherals and screen RAM was mapped between the 640K and 1024K. The 8086 had 16 bit data on external bus otherwise identical to 8088.
Additionally the 8086 and 8088 are not true 16bit CPUs but basically the 8085 with a few 16 bit instructions and only 64K memory blocks like the 8080/Z80/8085. Later a Z80 clone had segment page memory manager for 1024k and the 8bit Z80 in Amstrad PCW could access 512K.
So the 640K was really a limitation of the small segmented address space of the pseudo 16bit 8088 and 8086. The amount of contiguous RAM depended on if text, hercules, CGA, EGA or VGA to and extent. It was much later that TSRs (AKA dirvers) could be loaded into unused holes in the 1024k as early DOS didn't support it and early IBMs had 128K, 125k, 384k, 512K or 640K physical ram. Later 1M physical DRAM was used.
The first real 16bit IBM PC was the 286, but DOS used it as an 8086. Only UNIX flavours of OS used it as a flat 16M address space.
The PC and DOS held back PC computing nearly 10 years as it was really not much different to the CP/M and 8080/8085/Z80 8bit machines, just more standardised.