"RAM68K" "MEM68K"

Here will be something about RAM expansion boards that go to Amiga's 68000 dip-socket


No support for read-modify-write cycles of ram nor 68000. Stackable with other boards, if no space conflict. V6x,V5x smaller "footprint" than v4x. Compatibility with other boards not certain. Only either config in or out in v5x, selectable by programming cpld.

Cpld code

CPLD source code and jedec files Updates, bug fixes

Autoconfig connections

- Autoconfig signal wire connections are not needed if ram board is the either only autoconfig device in system or other cards config first without accessing e80000 area on 68000 socket.
- Autoconfig-in signal should be "tied" (jumpered) to low level (gnd) to enable ram autoconfig. (See board versions)
- But in CDTV, the DMAC chip is another autoconfig device. Use newer cpld code "force config after one other(the dmac)" and put high level (inactive) to config-in to prevent config first.
- Amiga 500 (and A1000) 86-position side slot edge connector has grounded(!) autoconfig-out contact at bottom side grounded on via at top side (Grounding could be cut, maybe drilling a little from top). Grounding could be replaced with pull-down resistor 4k7?
A config signal coming from a A590 might be connected to back side edge contact 11: an edge finger no-connection in a500, top side, opposite of grounded a500 conf.out) - pull down resistor could be added and possibly pull-up from some ram boards "removed".
- When using config-in of belonging to last Amiga 2000 Zorro-slot, the slot should be left *empty*. Amiga B2000 rev4.4 mainboard, config in of last zorro slot. also at pin 8 of 74LS32 (U606) and pcb via where wire soldered


Various styles sockets or pins could be found for 68000 connection (pictures of some at ide 68k page)

Testing socket left - failed socket right, part of it stuck to 68000 pin when removing the cpu

V61, 62, 64, 65, 66, 67

V61 V62 V64 V65 V66 V67
-if pull-down resistor on config-in, override by connecting to config-out. Or ground to override pull-up.
-cpld is xc9572xl in vqfp-64 package (part numbers and speed grades etc. can vary) -5 volt dram (used KM416C4100AS, maybe KM416C4104, suffixes for both can be AS,BS, and so on).
-4-position header/pads: config pins 2 at center, 2 grounds at edges
-Both autoconfig in and out signals on pads.
-V61 buffers weakly pulled down config-in to cpld and led. V62 buffers also config-out led.
-V64 has pull-up for config-in, can solder short to gnd to pull low.
-V65 removes buffer IC - pullup 4k7?, smd solder jumper to gnd on board
-v66 adds buffer back - 330Kohm resistor pull-down or pull-up (solder jumper select) -v66 adds buffers for reset, 7M clock, uds, lds, as, rw
-v67 makes buffer ics added in v66 "unused", and signals actually shorted by pcb tracks. -Some boards made to thin 0.6 or 0.8mm thickness, some boards with very large dip-64 drill holes: features to help piggy-back soldering the ram board to a dip-64 ide-interface board.

V59, 58

-V58 nearly the same as v59 (about 10 pcbs v58, 100 v59 manufactured)
-One config (either in or out) signal
-can have LED indicating config-signal status, and extra pull up (or down) resistor for autoconfig-input version.
JP2 Config-in/out (other pad gnd) and jtag location: board V59 schematic
Parts: 3.3 volt 4Mx16 dram tsop-50, edo (maybe fpm too), 4k refresh with cas-before-ras refresh. (part numbers to be added LGS GM71VS65163CLT, Toshiba TC5165165AFTS-60, Samsung K4E641612E-TC60, ..) VQFP-64 XC9572XL. 2 Tssop (or qsop, but ssop is too wide) 74 245 buffers, 3.3 volt with 5 volt tolerant i/o, "low noise" type (not too fast slew rate. I have used SN74LVCR2245APW with series output damping resistors.) Ferrite-bead / 0-Ohm jumper 1206 size, Regulator AP2210N-3.3, 2.2uF min. output (and input) capacitor. I've used 0603 decoupling 330nF(Y5U) (also 100nF X7R) in V59. One capacitor could be tantalum 10uF (10volt or more 0603,0805,1206 size), maybe as regulator output capacitor. C4 gnd via sinks heat, so to solder straight, fix +3v3 side first.

V43, 42, 40

The RAM chip is 5 volt KM416C4104 TSOP-50 package (suffix maybe AS, BS, CS...) pdf Samsung 4M x 16bit CMOS Dynamic RAM with Extended Data Out, with 4K refresh, cas-before-ras refreshing. (FPM version KM416C4100 might work too.) It is not very common, I got a couple by desoldering them from a 16 MByte SIMM, also 32 MB SIMMs.
V43 schematic board
LM3480 -3.3volt regulator used with 3.3volt XC9572XL TQFP-100, 10 capacitors (see pcb notes, could use also one 10uF tantalum 10V or more for dram), led with series resistor, connections to 68000 socket / 68000. Also 5 volt xc9572 should work probably, regulator replaced with jumper.
V42 schematic board jtag pins v40 pcb brd image v40, autoconfig pinout
v40 photo v40 pcb photo Schematic v40 (png image).