Apple II / II+ Dead Test ROM — Find the Bad RAM Chip in a Dead Machine

Dead Apple II or II+ — blank or garbage screen, no beep, won’t boot? Bad RAM is the most common cause, and this chip tells you exactly which RAM chip failed, even when the machine can’t boot at all.

What it is

A professionally programmed 24-pin diagnostic ROM that installs in your motherboard’s F8 ROM socket. It runs entirely from the ROM itself — it never uses the zero page or the stack — so it works even with completely dead RAM. Based on the open-source appleII_deadtest project (v1.0.2 by Adrian Black / misterblack1, Frank IZ8DWF, and David KI3V), designed and tested for the Apple II and II+..

How it works

• Install the chip and power on — the speaker beeps once to confirm the ROM is running.
• Runs a March-U memory test over main RAM (up to 48K) — about 90 seconds per full pass.
• End of pass: rising two-beep tone = RAM passed | low tone = fault found.
• The test repeats automatically and errors are cumulative — intermittent faults stay flagged.
• Beep codes pinpoint the failing data bit (1 beep = D0 … 8 beeps = D7), and the included chart maps each bit to the physical chip in each RAM row.

Beep codesSoundMeaningSingle startup beepDiagnostic ROM is runningLong low beep + 1–8 medium beepsZero page / stack error — beep count = bit D0 (1) through D7 (8)Brief high trill + 1–8 medium beepsPage error (address lines) — beep count = bit D0 (1) through D7 (8)Constant high trillAddress-decoding logic faultRising two-beep tone at end of passRAM passedLow tone at end of passRAM fault foundChip location map — 16K×1 DRAM rows

Count the beeps to get the failing bit, then find the chip in the row shown on the results grid:

BeepsBitRow C ($0000–$3FFF)Row D ($4000–$7FFF)Row E style="font-size: medium; font-weight: 400; text-align: start; scrollbar-width: thin; scrollbar-color: rgba(128, 128, 128, 0.4) transparent; color: rgb(34, 34, 34);">Example: page $19 with 3 beeps → D2 → row C → C6. The included printed insert explains the full results-grid decoding.

Compatibility

• Apple II and Apple II+ — installs in the 24-pin F8 ROM socket
• Also suitable for most Apple II / II+ clones

Installation

Power off and unplug, open the case, locate the F8 socket, swap the ROM (match the notch orientation), power on and listen. Full step-by-step instructions are printed on the included insert. Never insert or remove chips with the power on. Observe anti-static precautions. While this ROM is installed the computer will not boot normally — this is expected. Reinstall your original ROM to restore normal operation; the test changes nothing.

What’s included

• 1× Apple II / II+ Dead Test ROM chip — programmed and tested
• 1× printed one-page insert: installation steps, beep-code chart, results-grid decoding, and full chip location map

Shipping & Returns

Fast shipping within 1 business day.
Returns accepted within 30 days. Buyer pays return shipping unless item is defective.

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