Difference between revisions of "JAIR CPU Board"
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===Documentation and links=== | ===Documentation and links=== | ||
| + | Verifing my recolation of the 8 inch disk format. | ||
{{Blockquote|8-inch Systems | {{Blockquote|8-inch Systems | ||
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The first standard disk was the IBM 3740 format 8-inch SSSD disk 241Kb (77 tracks, one head, 26 each 128 byte sectors per track with a skew of six) disk. This was the disk format used for exchange between all the CPM-80 8-inch systems and software providers. http://www.nj7p.org/Computers/Disk%20Subsystems/floppies.html}} | The first standard disk was the IBM 3740 format 8-inch SSSD disk 241Kb (77 tracks, one head, 26 each 128 byte sectors per track with a skew of six) disk. This was the disk format used for exchange between all the CPM-80 8-inch systems and software providers. http://www.nj7p.org/Computers/Disk%20Subsystems/floppies.html}} | ||
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===z80pack=== | ===z80pack=== | ||
[http://schorn.ch/altair.html z80pack] makes use of [http://simh.trailing-edge.com/ simh] | [http://schorn.ch/altair.html z80pack] makes use of [http://simh.trailing-edge.com/ simh] | ||
Revision as of 17:20, 8 June 2016
Contents
Joint Altair Imsai Replacement CPU board
Learn about the JAIR CPU replacement board at John Monahan S100Computers.Com site.
This is an Altair and Imsai compatible CPU replacement board designed by Josh Bensadon. I purchased it from him assembled off eBay. Generally this board is only available bare with the user responsible for sourcing parts and construction. It can operate without any cards in an Altair or Imsai equipped with a front panel. I find it very useful in diagnosing other cards while rebuilding S-100 era computers.
Resources
Under construction
Documentation and links
Verifing my recolation of the 8 inch disk format.
8-inch Systems
These were the first floppy drives available in the mid 70s. They were initially designed by IBM as a method to load microcode into their large DASD disk controllers. Other manufacturers started to manufacture them as storage devices for the then beginning small computer market. Many 8080/8085/Z80 CPM-80 systems used these drives. These drives were large, heavy, and required +5V, -5V and 24V to operate. The media spun continuously although the heads were unloaded when not reading or writing. This introduced the head load and unload time to the FDCs. These drives were available in soft- and hard-sectored models. Media was not interchangeable between them soft- and hard-sectored models.
The first standard disk was the IBM 3740 format 8-inch SSSD disk 241Kb (77 tracks, one head, 26 each 128 byte sectors per track with a skew of six) disk. This was the disk format used for exchange between all the CPM-80 8-inch systems and software providers. http://www.nj7p.org/Computers/Disk%20Subsystems/floppies.html
z80pack
diskdefs
# jha 6 June 2016
# The JAIR post era Imsai Altair replacement S-100 card doesn't use skew
diskdef ibm-3740-noskew
seclen 128
tracks 77
sectrk 26
blocksize 1024
maxdir 64
skew 0
boottrk 2
os p2dos
end
Using cpmtools cpmls I read the directory specifying the disk definition to use for 0 skew
jeffa@tx2000ros:~/z80pack/cpmsim/disks$ cpmls -fibm-3740-noskew DISK-D.BIN
0:
asm.com
blinkem.com
ddt.com
dump.com
[...]
view.com
wm.com
wm.hlp
xmodem.cfg
xmodem.com
xsub.com
jeffa@tx2000ros:~/z80pack/cpmsim/disks$
I'll copy a test file created with vi on linux to the JAIR disk file
jeffa@tx2000ros:~/z80pack/cpmsim/disks$ cpmcp -fibm-3740-noskew DISK-D.BIN ../work/jtest.txt 0:
I copied the DISK-C.BIN file back to my SD card and placed in the JAIR card. It worked!
