486DX and BL2-66 use same system board.
Reply 8570 Upgrade OEM Planar [486DX version shown]
Alan Hightower won an auction for a 20MHz Model 70, and imagine his utter chagrin when he found a BL2-66 Upgrade board inside. I would have sent it back, "not as described", but he was too passive aggressive, and he didn't complain...
Anyways, thanks to Alan, we can be certain there is ONE 8570 upgrade board. It either has a LIF in U100 and a bare U110 [486DX board] or a BL2-66 soldered in U110 and a LIF socket in U100 [BL2-66 board].
Two Planar Upgrades Available
486BL2 66MHz, Option P/N32G3300 The IBM 486 BL2-66 includes an internal memory cache controller and 16KB memory cache. The clock speed operates at 66MHz for the internal operations and 33MHz for external operations.U100 5v 17x17 486 socket. Outline (and 19x19 array!) of a ZIF. POD hack? I have popped in a 486DX4-75 and it ran fine. The HMM calls this a "P23T Upgrade connectors"
U110 Outline for two different flat packs. My guess- 486SLC or 486SX.
J10 Power header for IDE drive (). From left to right (power connector edgecard towards CPU) +5v, 12V, GND
U25, U27 Outlines for Video DRAM
C&T was a fabless company, searching for 82Cnnn got me hits. DATASHEET
82C223 DMA Controller
82C226 System Peripherals Controller
82C321 CPU and MCA controller
82C322 Page/Interleave and EMS controller
82C325 Data/Buffer controller
Cirrus Logic CL-GD542x Data Book
Cirrus Logic CL-GD542x Technical Reference
IMI SC425 System Clock PLL Frequency Synthesizer Datasheet
LT1141CS Triple Bus-Line Transceiver Datasheet
CXK5864BM-10L High Speed CMOS Static RAM, 8Kx8, 28 Pin Datasheet
MT4C16257DJ-7 Dynamic RAM, Fast Page, 256K x 16, 40 Pin, Plastic, SOJ Datasheet
N8742AH MicroController, 8-Bit, 44 Pin, Plastic, PLCC Datasheet
NS16550AFV Universal Async Receiver / Transmitter with FIFOs Datasheet
PC16550CV 1 Channel, 1.5M bps, Serial Comm Controller, 44 Pin PLCC Datasheet
U35-U36 Supports 4MB or 16MB 70ns and 80ns Industry standard SIMMs. Up to 32MB memory support (31MB addressable)
The 8570 upgrade only supports 4MB and 16MB Industry
Standard Memory SIMMs. Memory transferred from
previous system board will not function on upgrade
IBM's 4MB Industry Standard SIMM, Feature
Code 7634, Option P/N92G7201 and a 16MB Industry
Standard SIMM, Feature Code 2011, Option P/N92G7204 or
P/N60G1622. Memory must be identical in size and speed
if using both memory SIMM sockets.
Rich Wolos grabbed a 16MB parity from his Lacuna 77 and it worked fine.
Just to Show this Means
Memory Expansion Adapters
33 MHz Clock
identifies source of 33MHz:
32 Bit Mode under W95
From Greg Frantz
I finally got in front of one of the machines. Here is what I manually added to get the system working.
Standard IDE/ESDI Hard Disk Controller (Change to
This will enable the HDD in 32-bit mode
and has also allowed the use of a 4x Toshiba
CD-ROM. To get the floppy to work, install the
Standard Floppy Disk Controller after getting the HDD
working. The other thing to note is that the
floppy had to be a Sony for me to get it working.
SVGA video up to 1024 x 768 pixels (1MB video memory standard)