Ed. This page was originally HERE.
Okay, biggie PS/2 questions answered. There are actually several different flavors of Model 70.
There still exists a overview of 8570 systems at IBM Canada, if you haven't visted them yet.
The reference diskette you will want to use for these machines will be the RF7080.EXE self-extracting file unless you happen to have a 70-486, in that case check out Louis Ohland's 70-486 page.
These machines should all be easy to cope with provided you give them 72-pin, gold-tinned parity SIMMs at least 85ns fast for all but AXX and BXX; those two will need faster refresh 80ns SIMMs. The FRUs to use would be 92F0104 (85ns) and 92F103(80ns). . . or you can do 'British Museum' approach and simply try a SIMM out and see how the machine responds - either with an error, or the 'Automatically Reconfigure (y/n)?' dialog. The virtue of the trial-and-error method is that no brain cells whatsoever get hurt, but it might involve repeatedly opening & closing the machine's case - and increasing the risk of an inadvertent static discharge to your system.
The AXX & BXX critters are constructed differently, they will allow you to put as much as 8MB on the planar in two 4MB SIMMs, all others have a maximum motherboard limit of 6MB divided into 3 2MB SIMMs. The maximum amount of memory any 8570 system will talk to is 16MB unless you do some creative finagling (See IBM Memory Expansion & BOPT103.EXE). This is due to the DMA (direct MEMORY access, get it?) controller only having 24 address lines - which gives you 16MB worth of individual addresses. Now while we can all stand around and criticize IBM for this shortsightedness, it might be helpful to remember the prices for SIMMs in about 1989 and what software demanded of a system then. You can still have a very nice system (multitasking, GUI-enhanced, TCP/IP-able) in 16MB or less if you pick the right software for it.
20Mhz -061 system w/ short planar
As I originally received my system, it had 4MB of RAM and an IBM 60MB hard disk, all slots open, and the 386 processor already replaced with the Cyrix Cx486DRx2 (the large green chip in the JPG image to the left). I've since improved it by filling out planar RAM to 6MB, adding the IBM 80386 Matched Memory Adapter card, 8514/A, and Kraft Serial/Game card (I don't know about games, but it's well worth the second physical serial port). I've also changed hard disks, first to an 80MB IBM ESDI, then finally to a 120MB ProCom PMC120 1/2 height drive that is compatible with IBM Direct Bus Attach/ESDI. And a second floppy drive. I've got an NEC SCSI host card I'd like to use... when I've got the bucks to blow on some external SCSI devices.
The machine has been run at least once beyond IBM's recommended operating temperature range. The fact that it has forgiven me speaks very well of the system's reliability. IBM's recommended range: 60 deg F - 90 deg F (15.5 deg C. - 32.2 deg C.) I got a mysterious TRAP E (page fault error) Wall thermometer said 110 deg F (42.3 deg C.) Add 20 deg to figure out what the core chip temps were... about 130 (54.5 deg C.) Ouch. We haven't done this again.
What's gone wrong: Well, nothing really that you wouldn't expect from a 10-year old computer that probably hasn't always gotten the best of care. I've so far only replaced the power supply (no beepy-beepy), and the Drive riser card (when the system failed to acknowledge that disk C: existed). Am on monitor number 3, keyboard number 2, battery number 2. These minor maintenance issues aside- the machine has provided faultless performance. Anybody know what the MTBF for a 8570 is?
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