I thought it would be a good time to provide an update to this thread. I have been getting messages from people on other forums who have stumbled upon this thread. After viewing another thread on this topic whereby the user had some initial success, I thought I'd revisit my work. That other thread is here,
https://68kmla.org/bb/index.php?threads/converting-acard-aec-7722-to-aec-7726.38935/It would seem that I had been doing nothing wrong, that is, I am using 8-bit PLCC32 EEPROMs and the BIOS binaries I was using are already intended for 8-bit EEPROMs. The problem is that these ACARD units are somewhat particular as to different combinations of host controllers, devices, and cables.
I am using AEC-7722IR with PCB version 1.8, which originally contained a TSOP-48 EEPROM and BIOS v3.77I. I removed this EEPROM and soldered on a PLCC32 socket and am using an SST 39SF040, 512Kx8 bit EEPROM (PLCC32). I have no problem using BIOS version 1.77B, which is for the non-IR version of the AEC-7722. At least for the particular combination of hardware I tested, it seems that you cannot use 50-pin narrow terminated SCSI cables via a male 68-pin to female 50-pin adapter. Also, I tried with and without the SE jumper set on the ACARD. I tested with an ISA SCSI card, the AHA-1520B, and a PCI Ultra160 based card, which also contained a 50-pin connector. The ACARD adapter worked if I connected it with a 68-pin cable to a host controller's 68-pin connector. If you want to connect the AEC-7722 to a SCSI host controller that only contains a 50-pin connector, you must use a female 50-pin to female 68-pin adapter on the host controller's connector, and use a 68-pin terminated cable. You cannot use the pin adapter on the ACARD side. Another user on the Vogons forum has also confirmed this finding.
When I ran a quick benchmark with Adaptec SCSIBench32 on an Adaptec Ultra160 host controller, and the CD-ROM returned about 30 MB/s for same sector tranfers. When the CD-ROM was connected to an ISA AHA-1520B host controller, it benched 2700 KB/s, which from my experience is near the max of what a 50-pin narrow card can achieve on a 16-bit ISA. I tried about a half-dozen CD/DVD-ROM drives. Most of them worked, but some do not. Various Lite-On and LG drives worked, but my Compaq and Toshiba drives did not. Another brand worked, but was abnormally slow. I also tried a SATA CD-ROM drive, first connected to a SATA-to-IDE adapter, then to the ACARD. It worked, but the performance was substantially slower than using a native IDE CD-ROM, that is, about 5 MB/s in the benchmarks vs. 30 MB/s.
Another observation was that I was unable to use DOS SCSI CD-ROM drivers when the CD-ROM was connected to the ISA AHA-1520B host controller. For some reason the ASPI2DOS.SYS file didn't want to load in config.sys. While I ensured the IRQ was different than the motherboard's native UltraWide SCSI controller, there may have been some other conflict. I don't know. I'd have to retest this on a motherboard without built-in SCSI. Booting into Windows 2000, I am able to use the ACARD CD-ROM on the AHA-1520B. Alternatively, I had no issue using DOS SCSI CD-ROM drivers w/ACARD on the motherboard's native UltraWide controller (AIC-7880P). Note the motherboard is a Intel PR440FX socket 8 with two Intel Pentium II Overdrive 333 MHz units installed, and 1 GB of buffered EDO 50 ns memory. I also used a Gateway motherboard with Athlon 950 slot A for testing. This board contains the Ultra 160 host controller.
Next, I had wanted to see if I could use the 7726Q and 7726H BIOSes on the 7722 because this would let me convert IDE hard drives to Ultra 160 SCSI. I say Ultra 160 because the Acard manuals mention the 7726 work up to Ultra160. I did my testing mostly with BIOS version 1.73Q for the AEC-7726Q. The answer is yes, IDE hard drives and CF cards will work with v1.69H and v1.73Q BIOSes on the AEC-7722. Some CF card models don't work, like some noname eBay special deal unit and a Transcend 133x 8GB. The CF cards which did work were the Transcend Industrial CF170, Sandisk Ultra, SanDisk ExtremePro, and Lexar Pro 600x. I also tested IDE Maxtor Diamond Max 9 Plus and Diamond Max 10.
I ran some quick benchmarks on an Athlon 950 system with a Ultra160 controller. Using Adaptec EZ-SCSI Deluxe v5.0 and SCSIBench32, I see that a 10K Seagate U320 HDD returns 78 MB/s sequential and 119 MB/s same sector. With the Diamond Max 9 Plus, I get 58 MB/s sequential and 106 MB/s same sector. With the Diamond Max 10, I get 65 MB/s sequential. I think this is pretty decent for using a bridge adapter. Unfortunately, I benched the CF cards on a the Intel PIIOD system with only a UltraWide controller (max 40 MB/s), so the comparison is not fair, but nonetheless, with a CF card on a slower host controller, I get 23 MB/s.
There are some caveats when using HDDs and CF cards on the AEC-7722 w/7726 BIOS; they are similar to that of using CD-ROMs, but with an extra limitation. It seems that hard drives and CF cards must be used on a 16-bit bus, meaning 68-pin only. Trying to use a 68-pin terminated SCSI cable with a female 50-pin to female 68-pin adapter on the 50-pin host controller side resulted in extremely slow performance. While the system was able to boot, it was slow - about 275 KByte/s slow.
In summary, CD-ROMs with 1.77B work fine with the PLCC32 adaption. They work fine on 8-bit (usually 50-pin) and 16-bit (usually 68-pin) SCSI buses. Hard drives and CF cards work on the AEC-7722 with 7726 BIOS versions 1.69H and 1.73Q, but only on 16-bit SCSI buses. This is in contrast to the AEC-7720U, which uses a different ACARD chipset, which can accomodate IDE hard drives and CF cards on 8-bit 50-pin SCSI buses.