Plasmo
Experienced Member
I recently acquired a batch of DiskOnModule (DOM) and upgraded my homebrew Z80 with DOM instead of compact flash. I'm curios about the performance difference between DOM and CF, so I made up three files each a megabyte in size and PIP them from one drive to another drive. With CP/M 2.2, CF took 103 seconds whereas DOM took 93 seconds. So with 3 megabytes read and 3 megabytes write, CF is 58Kbyte/s while DOM is 65Kbyte/s, about 10% improvement; hardly worth the trouble, really.
Since I have CP/M3 on the same homebrew, I thought I tried it as well. I was shocked: PIP copy of 3 megabyte files is 21 seconds with DOM and 37 seconds with CF. That's 285KByte/s with DOM and 162KByte/s with CF. So why is CP/M 3 disk operation so much faster than CP/M 2.2?
I looked into my CP/M2.2 BIOS, I did my own simple block/deblock and read/write files is with INIR and OTIR instruction. I'm inexperience with CP/M and they are simple BIOS routines. In CP/M 3, I didn't have to do blocking/deblocking, read/write files is using the same INIR and OTIR instructions. So the differences are CP/M 3's better file handling and their more efficient block/deblock algorithms. Really? 4.5 times better? That seems incredible.
Bill
Since I have CP/M3 on the same homebrew, I thought I tried it as well. I was shocked: PIP copy of 3 megabyte files is 21 seconds with DOM and 37 seconds with CF. That's 285KByte/s with DOM and 162KByte/s with CF. So why is CP/M 3 disk operation so much faster than CP/M 2.2?
I looked into my CP/M2.2 BIOS, I did my own simple block/deblock and read/write files is with INIR and OTIR instruction. I'm inexperience with CP/M and they are simple BIOS routines. In CP/M 3, I didn't have to do blocking/deblocking, read/write files is using the same INIR and OTIR instructions. So the differences are CP/M 3's better file handling and their more efficient block/deblock algorithms. Really? 4.5 times better? That seems incredible.
Bill