Editing Amstrad PCW 9256 Troubleshooting Guide (section)

== Start-up ==
Like the other PCWs, the 9256 has no boot ROM. At reset the hardware feeds the Z80 a fixed stream of bytes that builds a short boot program in RAM, and that program loads the first sector of the disc in drive A. Dot matrix and daisywheel PCWs use slightly different boot programs.<ref name="jehw">John Elliott, ''PCW Hardware''. Hosted as [[:File:PCW Hardware Reference (John Elliott).pdf]], described at [[Amstrad PCW Hardware Reference (John Elliott)]]. Section 2 (boot process), section 6.1 (the PCW8256/8512/9256/10 printer controller), sections 8.2–8.3 (drive decoding on the 9256, 9512+ and 10, and the controller probe).</ref> A blank screen with no disc in the drive is therefore normal.<ref name="acuc">Richard Lloyd, PCW article ("Fifty two years and counting"), ''Amstrad CPC User Club Magazine'' (ACUC) issue 1, June 2022. Scan at [https://archive.org/details/Amstrad-CPC-User-Club-01--ACUC-Magazine- archive.org]. Retrieved 2026-10-02. A PCW started without a disc shows a blank screen and beeps; a suitable disc gives a series of lines moving down the screen.</ref>

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''Start-up symptoms'''
! Symptom !! Probable cause !! Action
|-
| Nothing at all: no screen, no drive activity || No mains, F501 open, or a supply fault || Check the mains lead and plug. Check F501 (3.15&nbsp;A time-lag) on the monitor board; if it has blown, find the short before replacing it. Then measure the supply outputs (below).<ref name="sm9256" />
|-
| Blank screen and beeps, no disc || Normal || Insert a start-of-day disc.<ref name="acuc" />
|-
| Blank screen and beeps with a disc in the drive || Wrong or damaged disc, or a drive that cannot read it || Try a known-good system disc made for the 9256. LocoScript and CP/M versions written after the 9256 contain code to detect its floppy controller and 3.5-inch drives.<ref name="jehw" />
|-
| Screen dark but the machine loads (drive light, beeps) || Brightness turned down, or a monitor fault || Turn up the brightness, then check the horizontal oscillator and the sub-brightness setting (below).<ref name="sm9256" />
|}