Boomer6345
Member
- Joined
- May 9, 2012
- Messages
- 16
Posted earlier about adding floppies to this unit…also posted about adding a clock but that post seems to never have made it to the board. And, of course, I’ve posted my interest in getting an XT-IDE card…my project will not be complete without it!
Anyway…I have several questions for this project….let’s see what you gurus can help me with…
DRAM – I upgraded to populate the memory board with the full 1.2MB (5 banks of 256K each). Couple questions here. First, what speed memory should this machine use? It is an 8 Mhz 8088 running at zero wait states. I thought I read somewhere that this means I need 80 or 100 ns RAM…but the board has 150 ns RAM. That is what I ordered and added and it seems to be working fine. The number on all the chips is D41256C-15. Does that seem fast enough for 8 Mhz and zero wait states?
EMS – this PC’s main memory card has an EMS chip on it…but I cannot seem to get the Zenith emm.sys driver from Zenith OEM MS-DOS 3.21 or 3.30+ to work with it…the system just hangs as soon as I load the driver in config.sys. Any ideas?
Lastly…since it will be weeks or months (years???) before I may ever get an XT-IDE board…I ordered an older “MFM” hard drive and controller. I have the controller…the drive is on the way from overseas.
While I’ve been waiting for the drive….I researched the controller and drive combination and think I may have a compatibility issue.
The controller is: Western Digital WDXT-GEN Assy 61-000222-00
Here is the exact link to the card I bought on eBay:
http://www.ebay.com/itm/110875232615?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
The drive is: Seagate ST251-1
My research shows that is controller is “feature” limited to only support a specific 20MB drive. I went into the controller ROM through debug and started entering my theoretical drive parameter info as if I was going to format my non-existent ST-251-1 and it seems to take everything. But even if I pull off the low level format will the controller not work due to its firmware being hard coded for a certain drive type?
I tried to find other controllers on eBay that support the ST-251-1 drive (which seems like a common drive back in the day) but none of the MFM or RLL controllers seemed to list a drive type with parameters that match this drive. Again…any ideas?
Thanks!
- Ed
Anyway…I have several questions for this project….let’s see what you gurus can help me with…
DRAM – I upgraded to populate the memory board with the full 1.2MB (5 banks of 256K each). Couple questions here. First, what speed memory should this machine use? It is an 8 Mhz 8088 running at zero wait states. I thought I read somewhere that this means I need 80 or 100 ns RAM…but the board has 150 ns RAM. That is what I ordered and added and it seems to be working fine. The number on all the chips is D41256C-15. Does that seem fast enough for 8 Mhz and zero wait states?
EMS – this PC’s main memory card has an EMS chip on it…but I cannot seem to get the Zenith emm.sys driver from Zenith OEM MS-DOS 3.21 or 3.30+ to work with it…the system just hangs as soon as I load the driver in config.sys. Any ideas?
Lastly…since it will be weeks or months (years???) before I may ever get an XT-IDE board…I ordered an older “MFM” hard drive and controller. I have the controller…the drive is on the way from overseas.
While I’ve been waiting for the drive….I researched the controller and drive combination and think I may have a compatibility issue.
The controller is: Western Digital WDXT-GEN Assy 61-000222-00
Here is the exact link to the card I bought on eBay:
http://www.ebay.com/itm/110875232615?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
The drive is: Seagate ST251-1
My research shows that is controller is “feature” limited to only support a specific 20MB drive. I went into the controller ROM through debug and started entering my theoretical drive parameter info as if I was going to format my non-existent ST-251-1 and it seems to take everything. But even if I pull off the low level format will the controller not work due to its firmware being hard coded for a certain drive type?
I tried to find other controllers on eBay that support the ST-251-1 drive (which seems like a common drive back in the day) but none of the MFM or RLL controllers seemed to list a drive type with parameters that match this drive. Again…any ideas?
Thanks!
- Ed