Mike Chambers
Veteran Member
- Joined
- Sep 2, 2006
- Messages
- 2,621
with my 22 year old miniscribe just about dead, i've been looking at this SIIG 16-bit ISA IDE controller as a way to replace it with a more modern and much faster IDE drive. it has a jumper on it to modify the controller IRQ to either 14 or 15.
since an XT's IRQ limit is at 9, that obviously won't work right out of the box. i googled the ISA slot pinout, and saw that the connections for selecting IRQ's 14 and 15 are (of course) on the little extended 16-bit section which doesn't have anywhere to plug in on an 8-bit slot in an XT.
i have successfully used this card in an XT before just as a floppy controller and it worked fine with 1.44 MB drives, but seeing that the FDD controller IRQ is within an XT's range that shouldn't be surprising.
what i was considering trying is jumping the connection from the IRQ 14 or 15 pin over to the IRQ 5 pin which is what an XT uses to access hard drives. i am no electronic engineer, and you guys are all smart. does anybody think this will or will not work? would it cause any damage to the motherboard or controller card?
if nobody knows, i will probably just try it and let you guys know how it goes. theoretically i think i would only be able to address between cylinders 0 to 1023, heads 0 to 15, and sectors 1 to 63 from an 8-bit ISA bus. (8-bit ISA has a 20-bit wide addressing ability)
it'll for sure be smaller than what the drive i'd put in can handle. 1024*16*63*512 = 528,482,304 bytes but that sure beats the heck out of a 20 MB MFM!
since an XT's IRQ limit is at 9, that obviously won't work right out of the box. i googled the ISA slot pinout, and saw that the connections for selecting IRQ's 14 and 15 are (of course) on the little extended 16-bit section which doesn't have anywhere to plug in on an 8-bit slot in an XT.
i have successfully used this card in an XT before just as a floppy controller and it worked fine with 1.44 MB drives, but seeing that the FDD controller IRQ is within an XT's range that shouldn't be surprising.
what i was considering trying is jumping the connection from the IRQ 14 or 15 pin over to the IRQ 5 pin which is what an XT uses to access hard drives. i am no electronic engineer, and you guys are all smart. does anybody think this will or will not work? would it cause any damage to the motherboard or controller card?
if nobody knows, i will probably just try it and let you guys know how it goes. theoretically i think i would only be able to address between cylinders 0 to 1023, heads 0 to 15, and sectors 1 to 63 from an 8-bit ISA bus. (8-bit ISA has a 20-bit wide addressing ability)
it'll for sure be smaller than what the drive i'd put in can handle. 1024*16*63*512 = 528,482,304 bytes but that sure beats the heck out of a 20 MB MFM!