As the PC-1401 family was rather successful, Sharp released an
update three years later.
The two new models were named PC-1403 and PC-1403H.
The differences were not large, but very helpful. They had a better display,
with 24 instead of 16 characters on the same display area, and lowercase
letters could now be used. Thus, there was an additional SML key to switch
between uppercase and lowercase entry mode.
Moreover, matrix calculation functions had been added, such as addition, multiplication, inversion and determinant. They could be used in calculator mode only.
The hardware was based on a later incarnation of the SC61860 CPU, paced at 768
kHz. The RAM had also been expanded, with 8 KB in the PC-1403 (D4364G 8k x 8
static RAM), and generous 32 KB in the PC-1403H (D43256AG 32k x 8 static RAM).
The new functions also required a larger ROM (72 KB, LZ92K32 plus SC6976T).
Thanks again to Roman von Wartburg for this information.