Quantar Firmware upgrade to R020.14.048 with bare EEPROMs & KEEP your old TRN7477 wireline board. All you guys out there with a 'knickerless' Quantar from the UK, listen up- this one is especially for you. Since this is such a great hack, I figured it deserved an additional write-up with some clearer photos and additional info. This will allow you to upgrade the TTN4094 Station Control Module to current firmware without having a SIMM. Additionally, you can ALSO KEEP the TRN7477 wireline board and have it work. Using my method, you won't solder directly to the EEPROMs or bend its leads, which preserves them for any potential re-flashing in a programmer. This firmware upgrade is well worth the effort because this vintage of SCM came with R016 vintage firmware which is pretty atrocious- It doesn't even support V.24 linking for P25 plus has a ton of bugs. The original credit goes to acidhard in his post here: http://communications.support/threads/4344-Motorola-Quantar-upgrade-R20-14-038-when-there-is-no-non-volatile-memory-simm?highlight=non-volatile When all is said and done, you'll have performed the following: 1) Burned 7 PROMs total (1 for exciter, 4 for SCM, 2 for wireline board). 2) Modified your SCM sockets/ wiring 3) Installed the PROMs into their appropriate locations. You're going to need the following: PROMS 1x AM27C512-150 (DIP 28) or AT27C512R (DIP 28, OTP) 4x AM29F040B-90 (DIP 32) 2x AM27C010-70 (DIP 32) or AT27C010 (DIP 32, OTP) or GLS27SF010 (DIP 32, Flash) SOCKETS 4x DIP 32 Sockets w/flat style leads PROGRAMMER I personally had good luck with the mcumall GQ-4x (off the 'bay). Or use whatever you got that supports the above PROMs. MISC. Thin wire (I used wirewrap wire, #30) 1x 100ohm resistor Kapton tape (I suppose other tapes will work, but this is the good stuff) The basic premise of the SCM sockets/wiring mod is that you're: A) Fooling the SCM into thinking there is a SIMM module present by jumpering Presence Detect (PD) pins 80-79-75-74-73. See the SIMM spec sheet if you use different speed memory. B) Connecting the additional Address 18 (A18) line from the EEPROMs pin 1 to SIMM socket pin 34 C) Connecting the Chip Enable (CE) line from the EEPROMs pin 22 to SIMM socket pin 24 via 100ohm resistor D) Jumper SIMM slot pins 2-3. (Note: AstroSpectra said this isn't necessary, but on the original SIMM, these pins ARE jumpered). Only do this on a 4094 board. I have made a neat zip file which has everything you'll need in it. It contains detailed pictures, bin images and datasheets of the SIMM pinout and PROM pinout. Download the zip, and take a look at all the photos. Everything is pretty self-explanatory. Notes: - In the kapton_sockets photo, disregard the blue wires- I was experimenting with another wiring method. -Wireline FW version- it is not the matching version to SCM 20.14.048, but it seems to work just fine, even with V.24 linking. Wireline 20.10.816 is the latest version I know of that will work with the TRN7477 while also being compatible with the .048 SCM. The matching wireline version (20.14.003) will not work-it needs higher capacity PROMs and apparently doesn't have enough RAM to run it anyway. The only operational difference I noted is the "GET DELAYS" button function of an Astrotac does not work work when connected to a station with a 7477 wireline using 20.10.816 firmware. - In acidhard's original mod, the Write Enable (WE) pins are connected. I have found this to be unnecessary as we will not be flashing the PROMs in the SCM. Additionally, I think an error was made- Instead of connecting the PROMs to W0, W1,W2,W3 individually, the WE line of the EEPROMs should be commonly connected to W0 (Pin 5). The JEDEC SIMM standard treats memory modules in banks. In the 2MB SIMMs, there is only one bank of 4 devices. Incidentally, the Intellirepeater SIMM, is a 4MB unit w/ 2 banks of 4 devices (8 total). If I'm wrong on this, please correct me. - You can use PROMs with different speed values (the suffix of the part number indicates the speed) for the SCM, but you'll probably want to change the SIMM PD pin arrangement to indicate the device speed. I haven't tried other speed devices so I don't know how critical the speed setting on the PD pins is. It looks like the Quantars are happy with memory as slow as 150nS, but YMMV as usual. If you're lucky, your station may have come with UV erasable EPROMs for the exciter and wireline. If you don't have the circular Quartz window under the label, too bad- go and find some PROMs. There are many PROMs available on the bay, but watch out for counterfeits of course. Mouser still sells One Time Programmable versions for the wireline and exciter, but usually a better deal can be found on the 'bay. - If you have a station which intermittently boots up or won't read/write it's codeplug, check U655 to see if it's a Xicor brand chip. If it is, replace it with an Atmel brand ATHC64B (PLCC32 package). The Xicor EEPROM from these vintage of Quantars can be problematic. Once I swapped mine out, the problems disappeared. After you put a blank PROM in the socket, you'll be able to write a codeplug even thought the status light indicates "Station Fail" as long as the firmware is booting. Special Note: Do not try to read/write the ATHC64B in the GQ-4x using a PLCC adapter- as of 5/24/14, there is no database entry for the PLCC32 version- Only the DIP 28 package has an entry. The pinouts are wrong for the PLCC version and you will fry the chip.