ArchieX
Member
I just had the sudden urge to revisit a mystery that has left me... well, mystified, since the early 2000's!
I was just really getting into computers around this time and had a bunch of old systems that I was tinkering with, many of which I still own, and one of which is a blinged-out PC-AT: EGA monitor with stand, 84-key keyboard, 30MB hard disk, co-processor and AutoCAD with the tablet! I would have had a plotter with it too, but I simply didn't have the room to store that beast - it was huge!
It came with an IBM extended memory card that has two serial ports and a total of 12 30-pin SIMM sockets, two of which are populated with 1MB SIMM's giving a total of 2MB of extended memory. And the mystery is I've never been able to add more than 2MB of memory onto this card, and couldn't figure out why.
It has a row of 8 DIP switches, and leaving it in the configuration I originally found it in leaves me with 2MB visible by the system. Adding SIMMs will still only leave 2MB seen by the system; changing the DIP's randomly will stop that system from seeing that 2MB. The serial ports have never worked for me, leaving me to use another serial card to use the mouse.
Obviously the key to my mystery is the DIP switch settings, but I've never been able to find a manual or any online info for this card as to what settings will enable the use of more memory. I have deduced that the card needs 9-chip parity SIMMs, as that's what was installed on them originally; using 3-chip or 8-chip SIMMs in place of the originals will not work. I have tried other 9-chip SIMMs in place of the originals and they WILL be seen by the system.
It is a full-length 16-bit ISA card. It has a male DE-9 and a female DB-25 serial port. One bank of SIMM slots is labelled 'high byte", the other "low byte". The DIP switch is labelled 'S1' and has switches 4, 6 and 7 turned on; the rest are off.. The card is labelled in the upper left-hand corner "ASM 55X3543" and "EC A25158[4287]". A prominent metal-covered circuit is labelled "65X5770ESD / IBM 14".
My goal is to fully populate this card with as much memory as it can hold (12MB?) as well as getting both serial ports functional, so I can remove the other serial card.
I can provide an image of this card if it is requested. Any help given would be most appreciative.
I was just really getting into computers around this time and had a bunch of old systems that I was tinkering with, many of which I still own, and one of which is a blinged-out PC-AT: EGA monitor with stand, 84-key keyboard, 30MB hard disk, co-processor and AutoCAD with the tablet! I would have had a plotter with it too, but I simply didn't have the room to store that beast - it was huge!
It came with an IBM extended memory card that has two serial ports and a total of 12 30-pin SIMM sockets, two of which are populated with 1MB SIMM's giving a total of 2MB of extended memory. And the mystery is I've never been able to add more than 2MB of memory onto this card, and couldn't figure out why.
It has a row of 8 DIP switches, and leaving it in the configuration I originally found it in leaves me with 2MB visible by the system. Adding SIMMs will still only leave 2MB seen by the system; changing the DIP's randomly will stop that system from seeing that 2MB. The serial ports have never worked for me, leaving me to use another serial card to use the mouse.
Obviously the key to my mystery is the DIP switch settings, but I've never been able to find a manual or any online info for this card as to what settings will enable the use of more memory. I have deduced that the card needs 9-chip parity SIMMs, as that's what was installed on them originally; using 3-chip or 8-chip SIMMs in place of the originals will not work. I have tried other 9-chip SIMMs in place of the originals and they WILL be seen by the system.
It is a full-length 16-bit ISA card. It has a male DE-9 and a female DB-25 serial port. One bank of SIMM slots is labelled 'high byte", the other "low byte". The DIP switch is labelled 'S1' and has switches 4, 6 and 7 turned on; the rest are off.. The card is labelled in the upper left-hand corner "ASM 55X3543" and "EC A25158[4287]". A prominent metal-covered circuit is labelled "65X5770ESD / IBM 14".
My goal is to fully populate this card with as much memory as it can hold (12MB?) as well as getting both serial ports functional, so I can remove the other serial card.
I can provide an image of this card if it is requested. Any help given would be most appreciative.