Chapter 32 A microprogrammed implementation of EULER on IBM System/360 Model 30 385
The operators then, else, and, or and' have two trailer bytes containing a 16-bit absolute program address, e.g.,
Other operators with trailer bytes are label and the list-building operator.
Stack. The execution time stack consists of a sequence of 32-bit words. It contains block and procedure marks to control the processing of blocks and procedures and temporary values of the various types. The first 4-bit digit of a word in stack always is a type indicator. The format of these words is given in Fig. 3.
Variable area. The variable area is an area (32K bytes long) of 32-bit words used for the storage of values assigned to variables and lists (and also for auxiliary words in procedure descriptors; see type procedure in Fig. 3). The format of the entries is exactly the same as the format of the stack entries (see Fig. 3), the only exception being that a mark can never occur in the variable area.
Microprogramming the IBM System/360 Model 30 [Fagg et al., 1964]
Microprograms are sequences of microprogram words. A micro program word is composed of 60 bits and contains various fields which control the basic functions in the IBM System/360 Model 30 CPU. These basic functions are storage control, control of the
Fig. 3. Format of words in stack and variable area.