ACID SRAM Prof 8MB

ACID SRAM Prof is the next step to help Atari 8-bit owners to repair their computers at home, as in most of the cases dynamic RAM is faulty. On top of that this solution provides opportunity to upgrade memory to massive almost 8 megabytes.

FEATURES:

• Based on small FPGA and quad PSRAM
• Replaces base 64KB RAM in all Atari XL/XE models (and upgrades 600XL)
• Expands RAM to 128KB / 192KB / 256KB / 320KB, 576KB or 1088KB using PORTB. Additionally the RAM can be further expanded by 4096KB (Axlon) or up to 8144KB (Axlon + Axlon bis) - please refer to the manual above for detailed description
• Memory upgrade is configurable via software embedded in FPGA (accessible through ESC + RESET)
• Cold reset
• Replaces broken DELAY LINE chip in XL computers and many more ICs - refer to schematics below
• PCB thickness is 0.8mm
• Ultimate 1MB connector
• VBXE connector
• FPGA software upgradable via USB-C

IN THE BOX

• ACID SRAM Prof module
• MMU adapter
• 4pin wire (approximately 20cm long)

Disclaimer: 

If you are not familiar with soldering or you do not have proper tools, we can install the expansion for you. Please contact us to arrange installation.

If you are installing the device yourself, we will not take any responsibility for any damage to your hardware and the device will NOT be subject of any kind of warranty.

Step by step: 

• Locate CPU (SALLY, C014806) and MMU (C061618) on the motherboard.
• Remove old RAM chips (hint: this is actually not necessary; if your RAM chips do not get hot, you can remove resistors on data lines to RAM and keep chips intact) .
• If your CPU is not socketed, desolder it and solder in a socket. Install SRAM module in place of main CPU. Pin 1 of the SRAM module is at the bottom left on the picture.
  
• Insert CPU to SRAM module.
• If your MMU is not socketed, desolder it and solder in a socket. Install MMU module in place of MMU. Watch out on the notch in the socket to match notch on the MMU module.
• Insert MMU into MMU module.
• Connect with 4 pin wire between MMU module and SRAM module. Watch out for correct orientation of the cable (use marker on pin headers).
  
• Connect EXT_SEL pin to the motherboard.
  • Atari 800XL: pin 9 of 74xx08
  • All Atari models with Freddie chip (800XLF, 130XE, 65XE, 800XE): Freddie pin 3
  • IMPORTANT: if you have Atari XE without ECI port, EXT_SEL at Freddie pin 3 is connected to 5V directly. Before connecting ACID SRAM Prof, disconnect 5V from pin 3 and solder 10k resistor between pin 3 and 5V (pull up). Then connect the signal from the module.
• Please ensure that the newest firmware is installed, refer to the video above and FAQ on Lotharek's website

SRAM module completely replaces below parts that can be actually eliminated now. 

• 800XL

• XE (and majority of FREDDIE chip, than can be now  replaced even with CLK_DIVIDER built upon TTL 74)