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IBM PS/2 Model 25 & 30 Capabilities

Great Hierophant

Veteran Member
Joined
Mar 22, 2006
Messages
1,915
Location
Massachusetts, USA
Serial UART Type - 8250, Model 25 planar shows discrete 8250 chip.

Parallel Port - Unidirectional or Bidirectional?

I read that the floppy adapter does support the high density drives.

Any possibility of connecting a real speaker instead of the beeper on the 30? The 25 has an earphone connector.

IRQs and DMAs - Up to 7/3, as the 8525 has one 8237 DMA controller on board. If only 7/3, what IRQ does the mouse port use? My guess is 3. 0 for the System Timer, 1 for the Keyboard, 2 available (for video), 4 for the Serial, 5 for the Hard Drive, 6 for the Floppy Drive and 7 for the Parallel Port. DMA 0 for the RAM refresh, DMA 1 for the Hard Drive, DMA 2 for the Floppy Interface, DMA 3 free. Can any of this stuff be changed or disabled?
 

glitch

Veteran Member
Joined
Feb 1, 2010
Messages
4,964
Location
Central VA
There was an IBM voice synth card that was popular in the Model 25s...all of the ones we used in elementary school had them. They used the same TI voice synth as the Speak 'n Spell. I think I still have a few somewhere.
 

evildragon

Veteran Member
Joined
May 29, 2007
Messages
1,645
Location
Tampa Florida
The model 25 has a bi-directional parallel port, but hardly anything can use it because it's different to enable than a normal ps/2.. any standard EPP ISA card though will work though..
 

billdeg

Technician
Joined
Nov 18, 2003
Messages
3,872
Location
Landenberg, PA USA
There was an IBM voice synth card that was popular in the Model 25s...all of the ones we used in elementary school had them. They used the same TI voice synth as the Speak 'n Spell. I think I still have a few somewhere.

I'll trade you an 8085 SBC card for one or something else easy to ship. Interested? I have a special affinity to the PS/2 Model 25, it was the first computer that I purchased entirely with my own money, in college fall 1987. Came with the Collegiate Kit, which was an IBM version of Windows 1.04 made just for the model 25. If Ian is coming this weekend you can give to him and skip the shipping thing altogether.

????
 

IBMMuseum

Veteran Member
Joined
Aug 28, 2006
Messages
1,393
Serial UART Type - 8250, Model 25 planar shows discrete 8250 chip.

Parallel Port - Unidirectional or Bidirectional?

I read that the floppy adapter does support the high density drives...

Correct on the UART, the 16550 was the standard on microchannel planars (PS/2 models numbered as 50 or above). All PS/2 planar parallel ports were bi-directional in some form, able to use the "Data Migration Facility". The FDC on the 8086-based Model 25 and 30s was able to run the proprietary 1.44Mb drives, the Model 30 being a little more picky on brand than the Model 25.
 
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