AMPM: Alpha Micro AM-1200 Series

Despite its improvements over the AM-1000's idiosyncrasies, the AM-1200 is still the rarer unit (I do own two as it happens, but both are currently in varying states of non-operation). For this reason, it is not quite the landmark that the AM-1000 is. Like the AM-1000, the AM-1200 came in several derivative models, including the base 20MB hard drive-equipped AM-1200B, the 35MB AM-1200E and the 70MB AM-1200XP, the latter two having eight additional serial ports; we will illustrate both the vanilla 1200B and the 1200XP, which also has the 5.25" floppy drive option factory-installed (AM-210 FDC on an AM-220 I/O board).

Pictures

Portrait, of the AM-1200XP, but the 1200B is the same. Admittedly, this is where the 64:64C analogy breaks down, since the form factor was intentionally the same and the two units from the outside looked pretty much identical.

The front panel, however, is different. The reset button is a more stylish black recessed job, and a disk activity light was added; unlike the AM-1000, the specific variant letter is not stamped on the badge. The floppy drive in the AM-1200 series is the same as the AM-1000, using an AM-210 compatible FD controller, which is on an AM-220 board.

Rear ports, first of the AM-1200B. The base 1200B has five serial ports, one of which is a DB-25 (for some reason) and the others being "DB-9" (DE-9), and a single parallel port. The VCR interface is on the right. The bottom right cover plate is for a Centronics-style external interface, which is connected but not in use on this unit.

On the AM-1200XP (and AM-1200E), the port layout is the same but eight new ports are added on the lower right.

If we slide off the top, we get a look at the mainboard, which is fairly and unsurprisingly similar to the AM-1000 (take my word for it). The elongated DIP at the right next to the open position is the CPU; more about that in a second. This is of the AM-1200XP, but the AM-1200B is almost identical. Click the image for a 132K enlargement in a new window.

The top board is on a "hinge" and after removal of its restraining screws, simply lifts up. Notice the AM-1200XP's extra ports go directly to headers on the board, not to a separate card. There are jumpers next to the pin headers for configuring the individual port types.

The hard disk is at right, which is an SASI in this unit (but as of this writing had suddenly decided to not spin up). The floppy drive is in the middle and the AM-220 board is on the right, with the power supply underneath it. The streamer (when present) and floppy drive connect to the AM-220.

The AM-1000 was only ever powered by the 68000, but the AM-1200 was announced with the virtual memory capable 68010 although AMOS/L never supported virtual memory. However, what it was released with is another story: initially the unit was, just like the AM-1000, released with a 68000 (as shown in serial #6106, the 1200XP, at right). Alpha Micro later did indeed go back to the 68010 as announced, as shown in serial #52470 (the 1200B) at left. However, notice that the official model number for both units is as part of the AM-1000 series!

Performance

Potpourri

• Look on the bottom for a list of installed hardware. This is usually accurate, at least with regard to what it left the factory with.

• The 1200 series has the improved Self-Test ROMs, not the 1000's original Self-Test. This is a big improvement! The self-test is triggered, as in all Alpha Micro systems, by holding in the reset button as the computer is turned on. If there is a console terminal attached to a serial port, wait for "5b" to appear on the LEDs and then press the space bar repeatedly until the baud rate is sensed. Messages will then appear on the console as well as on the LEDs; a blinking code indicates an error. Code XX/YY indicates an alternating error code. The self-test LED codes are as follows:
  • 80 - initial config
  • 84 - sizing cache (84 - failed). If the self-test hangs at this point without blinking, this usually means the PROM cannot enumerate devices. Power down, unplug the floppy controller (if installed), the hard disk and the extra ports (if installed), and start the self-test again to see if this fixes the problem. If it does, restore connections until it fails again and suspect a controller issue with the offending device. If it doesn't, the mainboard is probably shot.
  • 90 - cache test (90/01-16 - failed bit 01-16, 8F/01-16 - display config failed)
  • 91 - memory test (9X/01-16 - failed bit 01-16, 8F/01-16 - display config failed)
  • 9c - timer test (9c - failed)
  • A0 - serial test (A0/1-13 - loopback failure port#1-13)
  • A8 - Winchester hard disk test (A8 - interface failed/not found, A9/11 - cylinder self test failed, AA/11 - find diagnostic cylinder failed, Ab/11 - r/w test failed)
  • b0 - VCR test [if installed] (b0 - interface failed/not found, b1 - RAM buffer failed, b2 - r/w test failed, b3 - handshake failed)
  • b8 - diskette test [if installed] (b8 - interface failed/not found, b9 - RAM buffer failed, bb - timeout, bC - status error)

• The boot switch settings for the 1200 are:

    dn up up dn  VCR, then floppy (if installed), then hard disk
    dn up dn up  Floppy only (no-op if not installed)
    up dn up dn  Floppy (if installed), then hard drive
    dn dn up dn  Streamer (if installed), then hard drive
  

  NOTA BENE: Displaying 'b' on the LED does not mean that the drive is bootable, it just means that the system is trying to boot! A common mistake is assuming the drive is intact when 'b' appears -- don't make this error yourself! Hook up a terminal and make sure you see the operating system coming up before you assume the disk is operating!

• Speaking of serial ports, for most installations you will connect your terminal at 9600bps (8N1), assuming a default system.