The ZX81 and ZX Spectrum manuals had the character code table (ASCII-ish on the Spectrum, something totally different on the ZX81) alongside all the Z80 mnemoni

The ZX81 and ZX Spectrum manuals had the character code table (ASCII-ish on the Spectrum, something totally different on the ZX81) alongside all the Z80 mnemonics and their hex and decimal values in the back. I think the Jupiter Ace manual might have had that too, but it's been a long time since I've even seen my copy of that.